| Autor: |
Marijane Russell, Gary L. Johnson, Sim Winitz |
| Rok vydání: |
1994 |
| Předmět: |
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| DOI: |
10.1016/s0076-6879(94)37072-9 |
| Popis: |
Publisher Summary Among the G-protein α subunits there are both common and unique functions encoded in the structure of the α -chain polypeptide. Common features include the functions involved in regulation of the α subunit itself: (1) guanosine-diphosphate/guanosine-5'-triphosphate (GDP/GTP) binding, (2) intrinsic GTPase activity, and (3) binding sites for association with βγ subunits. Unique functions for each α chain include (1) selectivity for regulating specific effectors and (2) selectivity for coupling to specific receptors. The unique functions for each α subunit allow selectivity in cellular responses to the environment and regulation of specific physiological signal functions (enzymes and ion channels). The α -subunit sequences involved in two of the common functions for all G proteins are highly conserved at the amino acid level. The sequences involved in contact and regulation by βγ complexes are less apparent in the primary sequence of G-protein α subunits. The sequences involved in the unique functions of receptor and effector interaction and regulation are also predictably diverse and nonconserved. The G proteins G s and G i regulate the common effector adenylyl cyclase. G s activates and G i inhibits adenylyl cyclase activity. G s and G i also preferentially couple to different receptors. For this reason, the α s and α i polypeptides have proved extremely valuable for characterizing the common and unique functions of G-protein α subunits by chimera and mutation analysis. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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